Tailoring of structural, electrical and magnetic properties of BaCo2 W-type hexaferrites by doping with Zr–Mn binary mixtures for useful applications

doi:10.1016/j.jmmm.2011.03.009

Journal of Magnetism and Magnetic Materials

Volume 323, Issue 16, August 2011, Pages 2137-2144

https://doi.org/10.1016/j.jmmm.2011.03.009 Get rights and content

Abstract

Single-phase W-type hexaferrite, BaCo₂Fe_16−2x(ZrMn)_xO₂₇ (x=0.0–1.0), has been synthesized by the chemical co-precipitation technique. Mössbauer analysis indicates substitution of Zr ions on tetrahedral (4e and 4f_IV) sites and Mn ions on the octahedral ‘4f_VI site’ at low-doped concentration when the concentration is increased Mn ions but show preference for the octahedral ‘2b site’. The highest enhancement in the value of the room temperature resistivity of 2.82×10⁹ Ω cm has been obtained by doping with Zr–Mn content of x=0.6. The dissipation factor increases from 6.49×10³ to 9.97×10³ at 10 kHz with the addition of Zr–Mn dopants. Such materials are potentially suitable for electromagnetic attenuation purposes, for microwave absorption and as radar absorbing material. High values of saturation magnetization (67 emu/g) and remanent magnetization (34.7 emu/g) are obtained for substitution level of x=0.4 making them suitable for data processing devices.

Highlights

► Zirconium ions preference is for f_IV sublattice while Mn ions prefer 4f_VI and 2b sublattices. ► Room temperature resistivity of up to 2.82×10⁹ Ω cm is obtained for doped hexaferrites. ► High value of saturation magnetization (67.0 emu/g), remanent magnetization (34.7 emu/g) and coercivity (1861 Oe) make doped hexaferrites to be utilized as data processing devices.

Introduction

Ferrites are important magnetic materials that, find its application in almost 70–80% of the electronic materials such as home appliances, communication equipments and data processing devices [1], [2]. Having a high coercivity and moderate magnetization, hexaferrites are valuable from technological point of view. W-type hexaferrites are suitable for competing in the field of magnetism because of their high saturation magnetization as compared to the most widely used other types of ferrites [3], [4], [5], [6], [7]. Furthermore, with large magneto-crystalline anisotropy in easy axis, W-type hexaferrites are applicable for both longitudinal and perpendicular recording media.

Owing to the crystallographic view, the cations with the exception of the Ba²⁺ ions in W-type ferrites occupy seven non-equivalent sub-lattices, i.e. 12k, 4f_VI, 6g, 4f (octahedral coordination), 4e, 4f_IV (tetrahedral coordination) and 2d (bipyramidal coordination) [8], [9]. However, there are only five magnetically non-equivalent sub-lattices from magnetic perspective, i.e. 4e and 4f_IV that merge into f_IV, magnetic sub-lattice while 6g and 4f combine to 2b sub-lattice and called as b magnetic sub-lattice [10]. All these sub-lattices are present in different number of R-blocks (Ba containing layer) and S-blocks (spinel layer) that construct W-type ferrites [11].

In the last few years variations in different properties of ferrites such as cation distribution, electrical resistivity, saturation magnetization, coercivity and remanence, were made possible by substitution of manganese ions. For example, Mn–Zn doped spinel ferrites, synthesized by combinatorial synthesis, show the effect of various additives on the formation of high performance materials by sintering them at lower temperature [12]. Synthesis of Mn–Zn doped spinel ferrites with Fe-poor composition and investigation of their electromagnetic properties found that the measured value of electrical resistivity (10⁵ Ω cm) is significantly higher than that of the Fe-rich Mn–Zn ferrite and the Curie temperature decreases with substitution of diamagnetic Zn ions [13]. Variations in the crystallite sizes were found to be due to Mn substitution in nickel ferrite, which in turn affected the structural and magnetic properties [14].

In the present work, important modification of structural, electrical and magnetic properties of W-type hexaferrites is achieved by doping with a relatively small amount of the transition metals. The modification of the above-mentioned properties is suitable for their applications in various electrical devices employed for industrial and military applications. The chemical co-precipitation technique [15] has been used to synthesize homogeneous nano-crystallites of hexagonal ferrites because of the simplicity of this technique with respect to both composition and morphology.

Section snippets

Materials

The raw materials utilized in the present work are BaCl₂·4H₂O (Analar 99%), Co(CH₃COO)₂·4H₂O (Merck 99%), Fe(NO₃)₃·9H₂O (Sigma-Aldrich 98%), ZrOCl₂·8H₂O (BDH 96%), Mn(CH₃COO)₂·4H₂O (Merck 98%), NaOH (Merck 98%) and Na₂CO₃ (Merck 99%).

Synthesis of BaCo₂Fe₁₆O₂₇ nanoparticles

Samples of composition BaCo₂Fe_16−2x(ZrMn)_xO₂₇ (x=0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by chemical co-precipitation method. For this stoichiometric ratio, the corresponding chemicals were dissolved in distilled water and thoroughly mixed to form a homogeneous

Structural analysis

X-ray diffraction patterns for BaCo₂Fe_16−2x(ZrMn)_xO₂₇ (x=0, 0.2, 0.4, 0.6, 0.8 and 1) hexaferrites along with the standard pattern (00-019-0098) are shown in Fig. 1. Pure W-type hexagonal ferrites are generally obtained by sintering at temperature ≥1273 K but we are able to synthesize a single W-hexaferrite phase at relatively low annealing temperature of 1193 K. The X-ray density (ρ_x), cell volume (V) and crystallite sizes (D) are calculated using the well-known equations [15], [16], [17] and

Conclusions

Zr–Mn doped BaCo₂ W-type hexaferrites with a nominal composition can be synthesized by chemical co-precipitation technique at a temperature of 1153 K that is comparatively much lower for W-type hexaferrites than that reported in literature. The XRD analysis conforms to the single-phase W-type hexaferrite and the SEM images show that the crystallites are more or less coagulated and the grain growth increased with increase in the dopant concentration. The lattice parameters increase with increase

Acknowledgment

Higher education commission of Pakistan (HEC) supported this work.

References (39)

R.B. Jotania et al.
J. Magn. Magn. Mater.
(2008)
A. Collomb et al.
J. Magn. Magn. Mater.
(1987)
W. Wang et al.
J. Alloys Compd.
(2008)
M.K. Shobana et al.
J. Magn. Magn. Mater.
(2009)
M.J. Iqbal et al.
J. Alloys Compd.
(2009)
D.M. Hemeda et al.
J. Magn. Magn. Mater.
(2008)
M.J. Iqbal et al.
Chem. Eng. J.
(2008)
P. Vaqueiro et al.
J. Solid State Chem.
(1996)
A.R. Bueno et al.
Mater. Chem. Phys.
(2007)
G. Albanese et al.
J. Magn. Magn. Mater.
(1994)

M.V. Rane et al.

J. Magn. Magn. Mater.

(1999)

A. Collomb et al.

J. Magn. Magn. Mater.

(1987)

M.J. Iqbal et al.

J. Magn. Magn. Mater.

(2008)

U.V. Chhaya et al.

Mater. Lett.

(1999)

D.M. Hemeda et al.

J. Magn. Magn. Mater.

(2007)

M. Maisnam et al.

Phys. B

(2005)

A.M. Abo El Ata. et al.

J. Magn. Magn. Mater.

(2005)

J.E. Bao et al.

Mater. Sci. Eng. B

(2003)

R.S. Devan et al.

Mater. Chem. Phys.

(2009)

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Tailoring of structural, electrical and magnetic properties of BaCo2 W-type hexaferrites by doping with Zr–Mn binary mixtures for useful applications

Abstract

Highlights

Introduction

Section snippets

Materials

Synthesis of BaCo2Fe16O27 nanoparticles

Structural analysis

Conclusions

Acknowledgment

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

J. Alloys Compd.

J. Magn. Magn. Mater.

J. Alloys Compd.

J. Magn. Magn. Mater.

Chem. Eng. J.

J. Solid State Chem.

Mater. Chem. Phys.

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

Mater. Lett.

J. Magn. Magn. Mater.

Phys. B

J. Magn. Magn. Mater.

Mater. Sci. Eng. B

Mater. Chem. Phys.

Tailoring of structural, electrical and magnetic properties of BaCo₂ W-type hexaferrites by doping with Zr–Mn binary mixtures for useful applications

Synthesis of BaCo₂Fe₁₆O₂₇ nanoparticles